The current cell phone jammer is full-band. It can shield all the 2G 3G 4G signals, 2.4G WIFI signals and Bluetooth signals under all the three operators of China Mobile, China Unicom and Telecom. Its principle is sent by itself. The frequency interferes with the mobile phone receiving the frequency from the base station and wireless router, so as to achieve the purpose of shielding them. Generally speaking, the working principle of the mobile phone signal jammer is that the frequency emitted by the jammer interferes with the normal frequency of the mobile phone receiving the base station, making the mobile phone unable to connect to the base station, and thus unable to make calls, receive and send text messages and surf the Internet.
Within a certain frequency range, the mobile phone and the base station are connected by radio waves, and data and sound transmission are completed with a certain baud rate and modulation method. The jammer scans from the low end frequency of the forward channel to the high end at a certain speed during operation. This scanning speed can cause garbled interference in the message signal received by the mobile phone. The mobile phone cannot detect the normal data sent from the base station, so that the mobile phone cannot establish a connection with the base station and achieve the purpose of shielding the mobile phone signal. The mobile phone appears to search the network, no signal, No service system, etc.
No matter what cell phone card you use, as long as the cell phone cards under China Mobile, China Unicom and China Telecom will be blocked. WIFI will also be blocked. Unless you use 5.8G WIFI to surf the Internet, because the standard configuration of the jammer does not shield 5.8G WIFI. However, some schools may let jammer manufacturers order 5.8G frequencies just in case, so this is not guaranteed to be absolutely foolproof.
Whether it is a high power jammer or a small signal shielding instrument, its principle is to interfere with the mobile phone to receive the normal frequency sent by the base station through its own frequency, so that the mobile phone cannot contact the base station, so as to achieve the purpose of shielding. The principle of shielding WIFI is actually that the signal jammer will send out the corresponding frequency when it is working to interfere with the mobile phone to receive the normal frequency sent by the router, so that the mobile phone cannot connect with the router and cannot access the Internet normally.
Mobile phone signal jammers are mainly used in some school examination rooms, dormitories, detention centers, military units and confidential meeting rooms, etc. So as long as you enter these places, your mobile phones will be shielded, and you will not be able to make calls, receive text messages, and access the Internet normally. There is no exception, and nothing can be set to avoid being blocked.